Upon finding himself trapped back in the time of Anthro the First Boy at the end of Final Crisis, Batman gets tired of waiting for DC editorial to send Booster Gold back in time to save him so it's time to do the job himself. Stealing a time machine from one of the fifty gajillion DC time villains randomly visiting the period he's stuck in(Lets say Per Degaton? Just cause?), Batman then looses the time machine in the belly of a T-Rex. After taming the T-Rex though, Batman uses its newly acquired time travelling abilities to port his way through DC history, teaming up with famous detectives and other heroes of the past to fight crime and injustice. Because he can't control the time dinosaur though, Batman doesn't know where he will end up and what each adventure will bring him.
And yes. Batman will totally get to punch Hitler in current continuity.
DC? You may now hire me.
via Nick Bachman